Long-Term Objective: Determine effective and safe utilization of viscous thixotropic fluid liner (TFL) to solve ameliorate existing significant problems involving stump prothesis interface. Our TFL knowledge and present successful use in wheelchairs/hospital beds should allow similar effectiveness to this proposed interface application. Specific Objective Phase I: 1. Evaluate and optimize proposed design and testing methodology, gathering additional pilot data and utilizing different thicknesses of TFL on below-knee temporary protheses, based on recent uncontrolled tests; 2. Design and test functional prototypes; 3. Conduct pilot study on ten subjects and 4. Develop enlarged Phase II design based on 1, 2, and 3 above encompassing applicability to temporary/permanent/below knee/above-knee prothesis combination to scientifically evaluate TFL effectiveness. Proposed preliminary Phase I design includes 10 intensive case studies exploring feasibility of utilizing matched groups of subjects. Benefits: TFL is a self-adjusting, consistently uniform pressure system that will minimize pain/discomfort; prevent/minimize infection, edema, nerve sensitivity, ripping of sutures; decrease recovery time from temporary to definitive prosthesis; reduce healthcare costs; provide shearing relief to better prepare stump for permanent prothesis; and will conform to bandages and dressings readily, while still providing a constant pressure on the stump.